This invention relates to pintle hook hitches for towing vehicles, and particularly pintle hook hitches with locking latch apparatus.
Conventional pintle hook hitches for trucks include an outwardly and upwardly curving horn over which a draw bar eye is placed for towing a trailer. To prevent the eye from inadvertently disengaging the pintle hook, a pivotal latch is customarily used. This latch pivots in a vertical plane from a lowered, closed and locked position over the horn, to a raised open position for connection or disconnection of the draw bar eye. Locking of the latch has for decades been achieved with an interference lock placed between the latch and another fixed part of the pintle hook body, to prevent the latch from pivotally raising until the lock is moved from its interference position. The lock has customarily been kept from so moving by a secondary lock in the form of a cotter pin or the like extended through the latch and attached to a chain to hopefully prevent it from becoming lost, as shown, for example, in U.S. Pat. No. 3,963,266.
In use of pintle hook hitches to tow a vehicle, the draw bar eye has some limited freedom of movement on the horn. This characteristic has been found objectionable by some users. Thus, several years ago employees of the assignee herein developed a pintle hook hitch which would have the eye pneumatically held when engaged over the horn. This hitch was designated the PH200 pintle hook hitch. Specifically, in this PH200 hitch 80 (FIGS. 8 and 9), an air operated plunger holds the eye to a small clearance relative to the horn inner surface, while above the plunger, the PH200 hitch has a pivotal latch 82 to close the pintle hook. The lock for this latch is a handle 84 which extends parallel to the latch and then bends about 90.degree. and extends through the latch and through a pivotal lock 88 which projects into the interference position between the latch and the pintle hook body. This prior PH200 structure is shown in FIGS. 8 and 9 herein. The handle and pivotal lock are secured together and are spring biased to one side of the latch where the pivotal lever is prevented from being pivotally raised by a shoulder 86 on the latch. By laterally shifting the handle and the pivotal lock, the pivotal lock escapes from beneath the shoulder, allowing the handle and thus the pivotal lock to be rotated to release the latch. While still holding the handle in this condition, the latch can be pivotally raised to release the draw bar eye from the hook.